public class Demo5 {
    public static int count = 0;
    synchronized public static void increase(){
        count++;
    }

    public static void main(String[] args) throws InterruptedException {
        Thread t1 = new Thread(() -> {
            for(int i = 0; i < 10000; i++){
                increase();
            }
        });
        Thread t2 = new Thread(() -> {
            for(int i = 0; i < 10000; i++){
                increase();
            }
        });
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        System.out.println("count = " + count);
    }
}
